The present invention discloses an annular cooling device for large-scale cylindrical shell, which comprises a plurality of inner jet devices and outer jet devices; the inner jet devices are arranged inside the cylindrical shell along the inner periphery; the outer jet devices are arranged outside the cylindrical shell along the outer periphery; each inner jet device and each outer jet device are oppositely arranged; the inner jet devices are used for spraying cooling medium to the inner wall of the cylindrical shell; the outer jet devices are used for spraying the cooling medium to the outer wall of the cylindrical shell; and the spray ranges of each inner jet device and each outer jet device in the axial direction of the cylindrical shell are both greater than the length of the cylindrical shell.

A heating system for drill steel pipe billet includes a feedback device configured to control distances d.sub.1 and d.sub.2 of three flamethrowers, a propulsion device, a positioning device, a heating device, a temperature measuring device and a conveying device. Heating temperature of the flamethrowers is controlled by an oxygen distribution box and a gas distribution box. A heating method for the drill steel pipe billet is also provided, in which a rolling forming method of gradient flame heating is adopted to control density of the rolled pieces and avoid internal defects of the drill steel caused by the same deformation of the traditional uniformly heated pipe billets. A radial temperature of the drill steel pipe billet is accurately controlled through the feedback device. Only one set of flamethrowers corresponding to drill steel pipe billets of different dimensions is required, and other devices are universal components, which will not be replaced.

A framework cooler (20) for cooling a steel strip (50), installed in a roller framework (11), in place of the work rolls (5) and their associated installation pieces (5a and 5b). The framework cooler (20) is sized to be installed into the roller framework (11) through the operator-side roller stands (1) of the roller framework (11). The cooler (20) includes a lower (21b) and an upper water tank (21a), each having a connection (22) for a coolant, and includes a plurality of cooling nozzles (23), or cooling tubes (23a) arranged in the depth direction (T) of the framework cooler (20) or at least one cooling slot (24) extending in the depth direction (T). The bottom and top sides of the steel strip (50) may be cooled.

A method for cold rolling rolled stock (2) in a mill train (1) with multiple roll stands (3 to 7). An upper limit temperature and/or a lower limit temperature is provided for a rolled stock temperature of the rolled stock (2) for at least one rolling pass, and the rolled stock temperature is controlled and/or regulated by at least one control or regulating measure such that during the at least one rolling pass, the rolled stock temperature does not exceed the upper limit temperature specified for the rolling pass and/or the rolled stock temperature does not fall below the lower limit temperature specified for the rolling pass.

In a tandem type cold rolling mill of a circulating oil-feeding system for continuously rolling a steel sheet by feeding a coolant serving as a rolling oil and a cooling water to each stand, an edge heater for heating both edge portions of the steel sheet to not lower than 60° C. as a steel sheet temperature at an entry side of a roll bite is arranged at an upstream side of the first stand in the cold rolling mill and a device for jetting a coolant having a concentration higher than that of the coolant fed to the firsts stand onto surfaces of both edge portions of the steel sheet is arranged between the edge heater and the first stand. The cold rolling mill can be used to roll a hard-to-roll material such as silicon or stainless steel sheet without causing an edge crack or sheet breakage in low-speed rolling.

A cooling device for cooling a metallic item and a method for operating the cooling device. Such cooling devices having a plurality of cooling bars arranged in parallel in groups for applying a coolant to the metallic item are known in the prior art. In order to be able to set a desired distribution function of the coolant over the width of the metallic item as precisely as possible, the cooling device provides that similar application regions in at least two cooling bars within a group are each formed differently with respect to their contour and/or with respect to their surface area.

A cooling device with variable cooling rate for treating metal materials, in particular for cooling steel sheets in plate mills, hot strip mills or thermal treatment lines, by means of a spray nozzle cooling system. The cooling device consists of at least two cooling bars one of each two cooling bars being situated on the lower side and the other on the upper side transversely to the sheet travel direction of the sheet and centrally between two roller table rollers and includes a spray nozzle cooling system with which a plurality of full jet nozzles and a plurality of full cone nozzles are associated, the full jet nozzles being arranged symmetrically to the full cone nozzles. A method for operating the cooling device according to the disclosure.

A hot and cold composite formed square and rectangular steel tube and a production method for the same are provided. The radius of an outer corner of the square and rectangular steel tube meets the following conditions: when t is less than or equal to 6 mm, R is greater than 0 and less than 2.0 t; when t is greater than 6 mm and less than or equal to 10 mm, R is greater than 0 and less than 2.5 t; when t is greater than 10 mm, R is greater than 0 and less than 3.0 t, wherein t is the wall thickness of a straight tube part of the square and rectangular steel tube; R is the radius of each of the outer corners of the four corners of the square and rectangular steel tube; and the wall thickness of each corner of the square and rectangular steel tube is between 1.0 t and 1.8 t.

A method for controlling or regulating the temperature of a steel strip in hot forming in a hot strip mill. A superordinate open-loop or closed-loop controller has a process model that predetermines the temperature development of the hot strip. The target values of the individual units are adjusted based on this predetermined temperature development.

A hot-rolled steel sheet includes a specific chemical composition, and includes a microstructure represented by, in vol %: retained austenite: 2% to 30%; ferrite: 20% to 85%; bainite: 10% to 60%; pearlite: 5% or less; and martensite: 10% or less. A proportion of grains having an intragranular misorientation of 5° to 14° in all grains is 5% to 50% by area ratio, the grain being defined as an area which is surrounded by a boundary having a misorientation of 15° or more and has a circle-equivalent diameter of 0.3 μm or more.